Low fitness is associated with metabolic risk independently of central adiposity in a cohort of 18-year-olds.

It is unclear whether cardiorespiratory fitness (CRF) remains associated with metabolic risk if controlled for central adiposity and other confounders; thus, the aim of this study was to investigate the independent effect of CRF on metabolic syndrome risk factors in relatively homogeneous age group of young adults. In this cross-sectional study, 828 participants performed CRF test on a cycle ergometer (W-max kg) and were categorized into sex-specific tertiles. Continuous metabolic syndrome risk score (MetS-score) was calculated as the sum of standardized scores of five metabolic syndrome risk factors: glucose, mean arterial pressure, low-density lipoprotein cholesterol, triglycerides, and total cholesterol/high-density lipoprotein cholesterol ratio. Low fitness group had higher values in all measured metabolic syndrome parameters, except for cholesterol parameters, compared to high fitness group. The unadjusted model indicated that CRF was negatively associated with clustered metabolic risk (=-0.116, P=.001). After the adjustment of smoking habits, sports training participation, and waist circumference, the association between CRF and MetS-score slightly increased (=-0.126; P<.001). Low CRF was associated with increased risk (OR=2.58 (95% CI 1.50-4.41)) for higher MetS-score after adjustment for potential confounders and waist circumference. The results of our study indicate that being highly fit increases the likelihood of having lower MetS-score for approximately 2 and 2.5 times independently of central adiposity compared to average and low fitness, respectively. In conclusion, it is highly important to improve CRF through regular exercise, not focusing just on body composition in young adulthood in every weight status group.